Insulated Concrete Forms

General Description

Extreme Structures LLC specializes in foundations using insulated concrete forms (ICFs). Basically ICFs are forms for poured concrete walls that stay in place as a permanent part of the wall and create a warm, solid foundation to build your SIP structure. The forms are made of foam insulation with pre-formed interlocking design that allow them to fit together much like children's blocks. The left-in-place forms not only provide a continuous insulation and sound barrier, but also a backing for drywall on the inside, and stucco, lap siding, or brick on the outside. Block systems have the smallest individual units, 1'4" x 4'. A typical ICF block is 10" in overall width, with a 6" cavity for the concrete.


Energy Efficiency

ICF walls do more than cut down on the biggest types of energy loss. The concrete gives them the heat-absorbing property, "thermal mass". This is the ability to smooth out large swings in temperature. It keeps the walls of the house warmer when the outdoor temperature hits its coldest extreme, and keeps the house cooler when the outdoor temperature is hottest. The walls themselves give back heat in winter and contribute to cooling in summer. These contributions give about 6% of the needed energy to the house for free. Attainable r-values from R-30 up to R-50 will help keep your house warm in the winter, cool in the summer. ICFs also have shown to be extremely resistant to destructive forces such as, tornados, earthquakes, fire, and hurricanes.

Fire-Resistant Capabilities

Fire ratings have been confirmed in so-called "fire-wall" tests. In these tests ICF walls were subjected to continuous gas flames and temperatures of up to 2000°F for as long as 4 hours. None of the ICF walls ever failed structurally. In contrast, wood frame walls typically collapse in an hour or less. Concrete walls have also proven more resistant to allowing fire to pass from one side of the wall to the other. This is especially of interest in areas with brush fires that could spread indoors. The fire wall test confirms this rule for ICFs once again. Part of the test measured how well the wall slows the passage of heat and fire from the side with the flame to the other side. The ICF walls tested did not allow flames to pass directly through. They also did not allow enough heat through to start a fire on the cool side for 2-4 hours. In contrast, wood frame walls typically allow both flame and fire-starting heat through in an hour or less.

The foam in ICFs are manufactured with flame-retardant additives. These prevent the foam from burning by themselves. If you hold a match to the material, it will melt away. Of course, in a house fire, the foam may be subjected to a constant flame from other materials burning nearby (wooden floors, fabrics, etc.). The "Steiner Tunnel Test" measures how much a material carries fire from an outside source. In the test, technicians line a tunnel with the material, light a fire at one end, then measure how far the flame spreads. The flames travel about one-fifth as far down a tunnel lined with ICF foam than a tunnel lined with wood.

Since you will have, strong, super insulated, airtight house, why not put it on a strong, super insulated foundation?

For more information on Build Block ICFs, visit:

What Our Customers Have To Say

We are proud to say that we are the only green built home in our town. Our new house was completed in March of 2008 by Jon Morehouse and Darren Harrington of Extreme Structures LLC of Denmark, WI. Our family was seeking to build a new home with many sustainable features, which is what drew us to the energy efficient qualities of Insulated Concrete Forms (ICFs) and Structural Insulated Panels (SIPs) during the summer of 2007. After completing the custom design and discussing our options with Extreme Structures, we decided that ICFs and SIPs technology was a great option for this project. The inherent energy efficient qualities of the construction and design has proven successful through our first winter in the new house as our monthly energy costs are approximately 2/3 of what they use to be, in a house that is almost twice as large and on two levels. In addition, our summer cooling bills have reduced significantly as well. Our experience in working with Extreme Structures and their partners was productive throughout, the project schedule and execution of design ran smoothly and was completed within budget requirements.

-David and Kristina

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